The present invention relates to a new and improved construction of a manually closable seal useful for closing the most different types of containers, packages, compartments, storage areas and so forth.
Generally speaking, the manually closable seal of the present invention is of the type comprising a seal body through which extends a channel or compartment. Within such channel there is mounted a holder for the retention of one end of a flexible strip, the other end of which is structured as a catch element. The catch element is designed to coact with locking elements arranged at the holder within the seal body.
Manually closable seals of this type are known under the designation "freight-car seals". They are employed for security reasons in conjunction with closure or locking devices for the most varied articles, wherein typically openings of the closure devices, in the closed position, overlap, so that the seal strip anchored at one end in the seal body can be introduced by means of its other end through these openings. Thereafter, the free end of the strip is introduced into the seal body, with the catch element irreversibly catching in the locking element, so that reopening of the closure which has been sealed in this manner only can be accomplished through destruction of the seal.
Such securing of a closure or lock is desired in many instances or, in fact, even prescribed by regulations or law, such as for instance in conjunction with closures for bags or sacks, especially mail pouches, for the sealing of the freight compartments of vehicles and so forth.
A safety seal of the previously mentioned type is known from Swiss Pat. No. 481,444. With this state-of-the-art seal the seal body is fabricated of one piece of a plastics material and extending therethrough is a channel having smooth walls. This channel constricts internally of the seal body while forming a step. The holder of the seal contains a locking element and is in the form of a metallic part. Such holder together with the end of a strip formed of plastic and secured to such holder, can be inserted from the side of the larger channel opening, together with the locking element leading, into the seal body. The step or stepped region within the channel serves as a stop, in order to prevent that the holder will move out of the seal body in the insertion direction. At the same time elements provided at the holder and effective in a direction opposite to the insertion direction, prevent undesirable departure of the inserted holder from the seal body.
This prior art seal, while relatively simple to fabricate, consisting of only three parts, nonetheless its handling requires a certain dexterity, in order to ensure that the individual parts are assembled in the correct position and sequence and to avoid faulty sealing. But in particular, however, this seal can no longer fulfil the strenuous requirements imposed upon the safeguarding against fake sealing which is possible at the present time through the use of suitable means employed by thieves and other unlawful intruders. It has been found that such individuals have been able to develop techniques by means of which it is possible for them to open and again close such prior art seals employing strips and catch elements formed of plastic, without visibly damaging the security seal.
Therefore, in practice, the tendency has been to return to the use of prior seal constructions of this type as have been disclosed, for instance, in Swiss Pat. No. 235,982 and the related Swiss Patent of Addition No. 244,992. The seal structures described in these patents have the strip formed by a braided wire. The base of the seal body possesses two tandemly arranged bowed-out portions or protuberances, at the shorter one of which there comes to bear the end knot of the wire which is secured at a flat locking disc, whereas in the longer protuberance there comes to bear a wire eyelet serving as a catch element and provided at the other end of the wire. This wire eyelet is then located adjacent a resilient tongue located at the locking disk and coming into engagement therewith and functioning as a counter-lock. This prior art type of seal, while fulfilling all of the security requirements, nonetheless consists of a relatively large number of metallic parts. Hence, its assembly is difficult to carry out and, in part, cannot be automated. The thus required manual work needed for the assembly of such seal renders the same unsuitable for inexpensive mass production, as the same would be needed for such a mass produced and throwaway article.